Field
The present disclosure relates to ocular optical systems and finder optical systems.
Description of the Related Art
In digital cameras such as digital still cameras, digital video cameras, digital single-lens reflex cameras, and mirrorless single-lens cameras, a finder optical system such as an optical finder and an electronic view finder is provided with an ocular optical system for enlarging an image displayed on an image display surface in the camera. Since the finder optical system is required to observe an image in a larger scale, it is necessary to increase the size of the image display surface or increase the magnification of the ocular optical system. However, an increase in the size of the image display surface causes an increase in the size of the finder optical system. Therefore, it is desired to increase the magnification of the ocular optical system while realizing size reduction of the finder optical system.
Japanese Laid-Open Patent Publication No. 2012-042844 discloses an ocular optical system, in order from a display surface side to an exit side, comprising: a first lens unit composed of a single lens having positive refractive power; a second lens unit composed of a bi-concave single lens having negative refractive power; and a third lens unit composed of a bi-convex single lens having positive refractive power.
Japanese Laid-Open Patent Publication No. 2011-197492 discloses an ocular optical system, in order from a display surface side to an exit side, comprising: a first lens unit composed of a meniscus lens having negative refractive power; a second lens unit having positive refractive power; and a third lens unit having positive or negative refractive power and composed of two lenses.
Japanese Laid-Open Patent Publication No. 2010-266776 discloses an ocular optical system, in order from a display surface side to an exit side, comprising: a first lens unit composed of a meniscus lens having positive refractive power; a second lens unit composed of a meniscus lens having negative refractive power; and a third lens unit composed of a single lens having positive refractive power.